From Division-Algebra Towers to Quark and Lepton Flavor: CKM and PMNS from Corner Selection

Two companion manuscripts presenting a structural approach to quark and lepton flavor mixing from division-algebra towers. "From Division-Algebra Towers to Quark Flavor Invariants: CKM from a Corner Selection" (33 pages) — derives the Cabibbo parameter λ = 1/(2√5) ≈ 0.2236, the hierarchy parameter A = √(2/3) ≈ 0.816, and the CP phase δ ≈ 64° from a vacuum idempotent and corner projector P₂ in C⊗H⊗O. "Lepton Mixing from Tower Geometry: A PMNS-Oriented Note" (8 pages) — extends the framework to leptons, showing that large PMNS mixing arises from a different orbit selection in the same axis+plane geometry. Key predictions:- λ = 1/(2√5) = 0.22361 (PDG: 0.22501 ± 0.00068)- A = √(2/3) = 0.8165 (PDG: 0.826)- δ = π/2 − 2θ_C ≈ 64.2° (PDG: 65.7° ± 1.5°) Associated code and numerical scripts available at DOI: 10.5281/zenodo.18364857